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more work on VM threaded I/O. Still nothing of usable

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antirez 2010-01-10 11:23:01 -05:00
parent 92f8e88204
commit 996cb5f704
1 changed files with 190 additions and 27 deletions
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217
redis.c
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@ -172,7 +172,7 @@
#define REDIS_MONITOR 8 /* This client is a slave monitor, see MONITOR */
#define REDIS_MULTI 16 /* This client is in a MULTI context */
#define REDIS_BLOCKED 32 /* The client is waiting in a blocking operation */
#define REDIS_IO_WAIT 64 /* The client is waiting for Virutal Memory I/O */
#define REDIS_IO_WAIT 64 /* The client is waiting for Virtual Memory I/O */
/* Slave replication state - slave side */
#define REDIS_REPL_NONE 0 /* No active replication */
@ -387,15 +387,22 @@ struct redisServer {
unsigned char *vm_bitmap; /* Bitmap of free/used pages */
time_t unixtime; /* Unix time sampled every second. */
/* Virtual memory I/O threads stuff */
pthread_t io_threads[REDIS_VM_MAX_THREADS];
/* An I/O thread process an element taken from the io_jobs queue and
* put the result of the operation in the io_done list. */
list *io_jobs; /* List of VM I/O jobs */
list *io_done; /* List of VM processed jobs */
* put the result of the operation in the io_done list. While the
* job is being processed, it's put on io_processing queue. */
list *io_newjobs; /* List of VM I/O jobs yet to be processed */
list *io_processing; /* List of VM I/O jobs being processed */
list *io_processed; /* List of VM I/O jobs already processed */
list *io_clients; /* All the clients waiting for SWAP I/O operations */
pthread_mutex_t io_mutex; /* lock to access io_jobs and io_done */
pthread_mutex_t io_mutex; /* lock to access io_jobs/io_done/io_thread_job */
int io_active_threads; /* Number of running I/O threads */
int vm_max_threads; /* Max number of I/O threads running at the same time */
/* Our main thread is blocked on the event loop, locking for sockets ready
* to be read or written, so when a threaded I/O operation is ready to be
* processed by the main thread, the I/O thread will use a unix pipe to
* awake the main thread. The followings are the two pipe FDs. */
int io_ready_pipe_read;
int io_ready_pipe_write;
/* Virtual memory stats */
unsigned long long vm_stats_used_pages;
unsigned long long vm_stats_swapped_objects;
@ -467,16 +474,18 @@ struct sharedObjectsStruct {
static double R_Zero, R_PosInf, R_NegInf, R_Nan;
/* VM threaded I/O request message */
#define REDIS_IOREQ_LOAD 0
#define REDIS_IOREQ_SWAP 1
typedef struct ioreq {
int type; /* Request type, REDIS_IOREQ_* */
#define REDIS_IOJOB_LOAD 0
#define REDIS_IOJOB_SWAP 1
typedef struct iojon {
int type; /* Request type, REDIS_IOJOB_* */
int dbid; /* Redis database ID */
robj *key; /* This I/O request is about swapping this key */
robj *val; /* the value to swap for REDIS_IOREQ_SWAP, otherwise this
* field is populated by the I/O thread for REDIS_IOREQ_LOAD. */
off_t page; /* Swap page where to read/write the object */
} ioreq;
int canceled; /* True if this command was canceled by blocking side of VM */
pthread_t thread; /* ID of the thread processing this entry */
} iojob;
/*================================ Prototypes =============================== */
@ -530,6 +539,9 @@ static robj *vmPreviewObject(robj *key);
static int vmSwapOneObject(void);
static int vmCanSwapOut(void);
static void freeOneObjectFromFreelist(void);
static void acceptHandler(aeEventLoop *el, int fd, void *privdata, int mask);
static void vmThreadedIOCompletedJob(aeEventLoop *el, int fd, void *privdata, int mask);
static void vmCancelThreadedIOJob(robj *o);
static void authCommand(redisClient *c);
static void pingCommand(redisClient *c);
@ -1379,6 +1391,14 @@ static void initServer() {
server.stat_starttime = time(NULL);
server.unixtime = time(NULL);
aeCreateTimeEvent(server.el, 1, serverCron, NULL, NULL);
if (aeCreateFileEvent(server.el, server.fd, AE_READABLE,
acceptHandler, NULL) == AE_ERR) oom("creating file event");
if (server.vm_enabled) {
/* Listen for events in the threaded I/O pipe */
if (aeCreateFileEvent(server.el, server.io_ready_pipe_read, AE_READABLE,
vmThreadedIOCompletedJob, NULL) == AE_ERR)
oom("creating file event");
}
if (server.appendonly) {
server.appendfd = open(server.appendfilename,O_WRONLY|O_APPEND|O_CREAT,0644);
@ -2418,9 +2438,14 @@ static void incrRefCount(robj *o) {
static void decrRefCount(void *obj) {
robj *o = obj;
/* REDIS_VM_SWAPPED */
if (server.vm_enabled && o->storage == REDIS_VM_SWAPPED) {
redisAssert(o->refcount == 1);
/* Object is swapped out, or in the process of being loaded. */
if (server.vm_enabled &&
(o->storage == REDIS_VM_SWAPPED || o->storage == REDIS_VM_LOADING))
{
if (o->storage == REDIS_VM_SWAPPED || o->storage == REDIS_VM_LOADING) {
redisAssert(o->refcount == 1);
}
if (o->storage == REDIS_VM_LOADING) vmCancelThreadedIOJob(obj);
redisAssert(o->type == REDIS_STRING);
freeStringObject(o);
vmMarkPagesFree(o->vm.page,o->vm.usedpages);
@ -2430,8 +2455,10 @@ static void decrRefCount(void *obj) {
server.vm_stats_swapped_objects--;
return;
}
/* REDIS_VM_MEMORY */
/* Object is in memory, or in the process of being swapped out. */
if (--(o->refcount) == 0) {
if (server.vm_enabled && o->storage == REDIS_VM_SWAPPING)
vmCancelThreadedIOJob(obj);
switch(o->type) {
case REDIS_STRING: freeStringObject(o); break;
case REDIS_LIST: freeListObject(o); break;
@ -2453,7 +2480,13 @@ static robj *lookupKey(redisDb *db, robj *key) {
robj *val = dictGetEntryVal(de);
if (server.vm_enabled) {
if (key->storage == REDIS_VM_MEMORY) {
if (key->storage == REDIS_VM_MEMORY ||
key->storage == REDIS_VM_SWAPPING)
{
/* If we were swapping the object out, stop it, this key
* was requested. */
if (key->storage == REDIS_VM_SWAPPING)
vmCancelThreadedIOJob(key);
/* Update the access time of the key for the aging algorithm. */
key->vm.atime = server.unixtime;
} else {
@ -2789,9 +2822,23 @@ static int rdbSaveStringObjectRaw(FILE *fp, robj *obj) {
static int rdbSaveStringObject(FILE *fp, robj *obj) {
int retval;
obj = getDecodedObject(obj);
retval = rdbSaveStringObjectRaw(fp,obj);
decrRefCount(obj);
if (obj->storage == REDIS_VM_MEMORY &&
obj->encoding != REDIS_ENCODING_RAW)
{
obj = getDecodedObject(obj);
retval = rdbSaveStringObjectRaw(fp,obj);
decrRefCount(obj);
} else {
/* This is a fast path when we are sure the object is not encoded.
* Note that's any *faster* actually as we needed to add the conditional
* but because this may happen in a background process we don't want
* to touch the object fields with incr/decrRefCount in order to
* preveny copy on write of pages.
*
* Also incrRefCount() will have a failing assert() if we try to call
* it against an object with storage != REDIS_VM_MEMORY. */
retval = rdbSaveStringObjectRaw(fp,obj);
}
return retval;
}
@ -2940,12 +2987,14 @@ static int rdbSave(char *filename) {
}
/* Save the key and associated value. This requires special
* handling if the value is swapped out. */
if (!server.vm_enabled || key->storage == REDIS_VM_MEMORY) {
if (!server.vm_enabled || key->storage == REDIS_VM_MEMORY ||
key->storage == REDIS_VM_SWAPPING) {
/* Save type, key, value */
if (rdbSaveType(fp,o->type) == -1) goto werr;
if (rdbSaveStringObject(fp,key) == -1) goto werr;
if (rdbSaveObject(fp,o) == -1) goto werr;
} else {
/* REDIS_VM_SWAPPED or REDIS_VM_LOADING */
robj *po, *newkey;
/* Get a preview of the object in memory */
po = vmPreviewObject(key);
@ -6654,7 +6703,8 @@ static int rewriteAppendOnlyFile(char *filename) {
int swapped;
key = dictGetEntryKey(de);
if (!server.vm_enabled || key->storage == REDIS_VM_MEMORY) {
if (!server.vm_enabled || key->storage == REDIS_VM_MEMORY ||
key->storage == REDIS_VM_SWAPPING) {
o = dictGetEntryVal(de);
swapped = 0;
} else {
@ -6831,9 +6881,31 @@ static void aofRemoveTempFile(pid_t childpid) {
unlink(tmpfile);
}
/* =============================== Virtual Memory =========================== */
/* Virtual Memory is composed mainly of two subsystems:
* - Blocking Virutal Memory
* - Threaded Virtual Memory I/O
* The two parts are not fully decoupled, but functions are split among two
* different sections of the source code (delimited by comments) in order to
* make more clear what functionality is about the blocking VM and what about
* the threaded (not blocking) VM.
*
* Redis VM design:
*
* Redis VM is a blocking VM (one that blocks reading swapped values from
* disk into memory when a value swapped out is needed in memory) that is made
* unblocking by trying to examine the command argument vector in order to
* load in background values that will likely be needed in order to exec
* the command. The command is executed only once all the relevant keys
* are loaded into memory.
*
* This basically is almost as simple of a blocking VM, but almost as parallel
* as a fully non-blocking VM.
*/
/* =================== Virtual Memory - Blocking Side ====================== */
static void vmInit(void) {
off_t totsize;
int pipefds[2];
server.vm_fp = fopen("/tmp/redisvm","w+b");
if (server.vm_fp == NULL) {
@ -6864,12 +6936,21 @@ static void vmInit(void) {
* file system when Redis exists. */
unlink("/tmp/redisvm");
/* Initialize threaded I/O */
server.io_jobs = listCreate();
server.io_done = listCreate();
/* Initialize threaded I/O (used by Virtual Memory) */
server.io_newjobs = listCreate();
server.io_processing = listCreate();
server.io_processed = listCreate();
server.io_clients = listCreate();
pthread_mutex_init(&server.io_mutex,NULL);
server.io_active_threads = 0;
if (pipe(pipefds) == -1) {
redisLog(REDIS_WARNING,"Unable to intialized VM: pipe(2): %s. Exiting."
,strerror(errno));
exit(1);
}
server.io_ready_pipe_read = pipefds[0];
server.io_ready_pipe_write = pipefds[1];
redisAssert(anetNonBlock(NULL,server.io_ready_pipe_read) != ANET_ERR);
}
/* Mark the page as used */
@ -7056,6 +7137,10 @@ static robj *vmGenericLoadObject(robj *key, int preview) {
/* Plain object loading, from swap to memory */
static robj *vmLoadObject(robj *key) {
/* If we are loading the object in background, stop it, we
* need to load this object synchronously ASAP. */
if (key->storage == REDIS_VM_LOADING)
vmCancelThreadedIOJob(key);
return vmGenericLoadObject(key,0);
}
@ -7212,6 +7297,86 @@ static int deleteIfSwapped(redisDb *db, robj *key) {
return 1;
}
/* =================== Virtual Memory - Threaded I/O ======================= */
/* Every time a thread finished a Job, it writes a byte into the write side
* of an unix pipe in order to "awake" the main thread, and this function
* is called. */
static void vmThreadedIOCompletedJob(aeEventLoop *el, int fd, void *privdata,
int mask)
{
char buf[1];
int retval;
REDIS_NOTUSED(el);
REDIS_NOTUSED(mask);
REDIS_NOTUSED(privdata);
/* For every byte we read in the read side of the pipe, there is one
* I/O job completed to process. */
while((retval = read(fd,buf,1)) == 1) {
redisLog(REDIS_DEBUG,"Processing I/O completed job");
}
if (retval < 0 && errno != EAGAIN) {
redisLog(REDIS_WARNING,
"WARNING: read(2) error in vmThreadedIOCompletedJob() %s",
strerror(errno));
}
}
static void lockThreadedIO(void) {
pthread_mutex_lock(&server.io_mutex);
}
static void unlockThreadedIO(void) {
pthread_mutex_unlock(&server.io_mutex);
}
/* Remove the specified object from the threaded I/O queue if still not
* processed, otherwise make sure to flag it as canceled. */
static void vmCancelThreadedIOJob(robj *o) {
list *lists[3] = {
server.io_newjobs, server.io_processing, server.io_processed
};
int i;
assert(o->storage == REDIS_VM_LOADING || o->storage == REDIS_VM_SWAPPING);
lockThreadedIO();
/* Search for a matching key in one of the queues */
for (i = 0; i < 3; i++) {
listNode *ln;
listRewind(lists[i]);
while ((ln = listYield(lists[i])) != NULL) {
iojob *job = ln->value;
if (compareStringObjects(job->key,o) == 0) {
switch(i) {
case 0: /* io_newjobs */
/* If the job was not yet processed the best thing to do
* is to remove it from the queue at all */
decrRefCount(job->key);
if (job->type == REDIS_IOJOB_SWAP)
decrRefCount(job->val);
listDelNode(lists[i],ln);
break;
case 1: /* io_processing */
case 2: /* io_processed */
job->canceled = 1;
break;
}
if (o->storage == REDIS_VM_LOADING)
o->storage = REDIS_VM_SWAPPED;
else if (o->storage == REDIS_VM_SWAPPING)
o->storage = REDIS_VM_MEMORY;
unlockThreadedIO();
return;
}
}
}
unlockThreadedIO();
assert(1 != 1); /* We should never reach this */
}
/* ================================= Debugging ============================== */
static void debugCommand(redisClient *c) {
@ -7377,8 +7542,6 @@ int main(int argc, char **argv) {
if (rdbLoad(server.dbfilename) == REDIS_OK)
redisLog(REDIS_NOTICE,"DB loaded from disk");
}
if (aeCreateFileEvent(server.el, server.fd, AE_READABLE,
acceptHandler, NULL) == AE_ERR) oom("creating file event");
redisLog(REDIS_NOTICE,"The server is now ready to accept connections on port %d", server.port);
aeMain(server.el);
aeDeleteEventLoop(server.el);